The British Government is a "long, long, long way" from being able to lift coronavirus lockdown restrictions in England, the Health Secretary, Matt Hancock, has warned.
Mr Hancock said there was evidence that restrictions in place were having an impact while the vaccination programme was making "brilliant progress".
However, he said that case numbers were "incredibly high" and the NHS remained under intense pressure.
"There is early evidence that the lockdown is starting to bring cases down but we are a long, long, long way from being low enough because the case rate was incredibly high," he told Sky News's Sophy Ridge on Sunday programme.
"You can see the pressure on the NHS - you can see it every day."
Mr Hancock said that while he hoped schools in England could reopen by Easter, it would depend on the levels of infection in the community at that time.
"We have got to look at the data, we have got to look at the impact of the vaccination programme," he said.
"The Education Secretary (Gavin Williamson) has said that we will ensure schools get two weeks' notice of return. I don't know whether it will be then or before then. We have got to watch the data."
Meanwhile Britain has detected 77 cases of the variant of Covid-19 first detected in South Africa, Mr Hancock said.
He said all 77 cases were connected to travel from South Africa and were under close observation, as were nine identified cases of a variant first identified in Brazil.
"They are under very close observation, and we have enhanced contact tracing to do everything we possibly can to stop them from spreading," he said during an interview on BBC television.
Oxford professor Anthony Harnden, deputy chair of a scientific committee on vaccination that advises the government, said the South African and Brazilian variants were of concern because Covid-19 vaccines may not be effective against them.
"The new variants abroad are a real worry. The South African and the Brazilian Amazonian ones, there are hints that there will be vaccine escape," he said on Sky News, adding that new variants would keep appearing around the world.
Britain has the highest death toll in Europe from Covid-19, at close to 100,000, and has been in lockdown for most of January with hospitals struggling to cope with record numbers of seriously ill patients.
The government has attributed the high transmission rates that led it to impose the lockdown in part to a highly contagious variant first identified in southeast England and now prevalent in many areas.
Prime Minister Boris Johnson said on Friday this variant may be associated with a higher level of mortality, although scientists have said the evidence on that remained uncertain, a message Mr Hancock re-emphasised this morning.
"The scientists do think that it may be more deadly, and they've put various estimates on that from about 10% more deadly to a bit more than that, we are not exactly certain about how much more deadly," he said on Sky News.
"In a way, for all of us, that doesn't matter, what matters is we have got to get this virus under control and the only way you do that is by stopping the social contact and following the rules," he said.
Additional reporting Reuters